The sample app's from app galery are looking great! As developer I get an idea of possible implementation when reviewing them, but I do wonder how Mendix did develop them. Read it as a curiousity towards the holistic Mendix best practices when developing such app's AND the possibility of making those practices even better TOGETHER with the community, like on Github (you can ofcourse publish on Github too :-) )
I think by releasing the source of sample app's all developers and customers could and would benefit from it, better models/logic/ui and may due to the reusability also time-to-market reduction for the customers.
Besides some commercial arguments against it, I personally think that at the end there would be more positive effects for all of us.
I am wondering what other developers and Mendix think about this idea.